More specifically, the invention relates to a method for manufacturing a vehicle interior trim part intended for covering an airbag, comprising the steps of:
a) providing a support having an opening;
b) providing a chute channel defining a passage to guide deployment of the airbag and a cover member adapted to cover the passage and fastened to said chute channel thereon;
c) fastening the chute channel to the support;
d) bringing a mold element to face the support and chute channel so as to define a closed cavity; and
e) injecting foam into the cavity.
Conventionally, in such manufacturing methods, the chute channel is fastened to the support by elastically interlocking or clipping into place, with a foam seal secured to the chute channel resting on the support all around the periphery of the opening.
However, such a technique is not entirely satisfactory, particularly in terms of reliability and repeatability of the seal so formed between the chute channel and the support, as well as in terms of reliability of operation of a trim part obtained by such a method.
Another known technique is to fasten the chute channel to the support by welding, especially by vibration welding or ultrasonic welding, the chute channel and the support being made of plastic.
Although this results in a reliable seal between the chute channel and the support, such a technique has the drawback of being particularly expensive to implement, as the vibration or ultrasonic welding machines represent a significant investment and occupy significant space at the manufacturing site.
In addition, fastening by ultrasonic or vibration welding of the chute channel to the support imposes certain design constraints on one and/or the other of these elements, in particular due to the need to provide welding ribs on these elements that are intended to melt under the effect of the ultrasound or vibration and form the seal between the chute channel and the support at the end of this step of fastening the two elements. The presence of such welding ribs increases the complexity of the mold design used to produce, for example by injection molding, the chute channel and/or the support and thereby adds a significant additional cost to the manufacturing process.